Sheet gripping control mechanism for printing machines



Aug. 26, 1969 o. RUDOLPH 3,463,484

SHEET GRIPPING CONTROL MECHANISM FOR PRINTING MACHINES Filed July 12. 1967 s Sheets-Sheet 1 FIG.4 P FIG. 5

6, 1969 o. RUDOLPH 3,463,484

SHEET G RIPPING CONTROL MECHANISM FOR PRINTING MACHINES Filed Juiy 12, 19s"! s Sheets-Sheet 2 INVENTOR OTFR IE D RUDOLPH 26, 19 o. RUDOLPH SHEET GRIPPING CONTROL MECHANISM FOR PRINTING MACHINES Filed July 12, 1967 3 Sheets-Sheet :5

FIG. 9

FIG. 8

INVENTOR OTFRIED RUDOLPH United States Patent Oflice 3,463,484 Patented Aug. 26, 1969 3,463,484 SHEET GRIPPING CONTROL MECHANISM FOR PRINTING MACHINES Otfried Rudolph, Dresden, Germany, assignor to VEB Druckmaschinenwerk Planeta, Radebeul, Germany Filed July 12, 1967, Ser. No. 652,943 Int. Cl. B65h 29/02; B41f 1/30, 21/04 U.S. Cl. 271---82 4 Claims ABSTRACT OF THE DISCLOSURE and the coupling rod is coaxial with the swing axis of the whole gripping system.

The present invention relates to a gripper control mechanism for a sheet gripper system in a sheet turning device and, more particularly, to a control mechanism for a sheet gripping system in a multicolor rotary printing machine with successive printing units, where between the successive printing units one or more sheet transfer cylinders are arranged.

For the turning of the sheet between successive printing units it is known to employ two gripping systems each being mounted on a swing shaft supported eccentrically on the rotary transfer cylinder. During the rotation of the transfer cylinder, both gripper sets are swung toward the center of the transfer cylinder and toward each other in order that the sheet might be gripped by the first gripper set and transferred to the second one. After the sheet delivery has been accomplished, both gripper sets are swung out again.

The known gripping set consists essentially of a number of support arms consecutively aligned on a swing shaft and carrying a pivotable gripper shaft provided with fixed- 1y mounted grippers on the one hand and, opposite to the grippers, the gripper stop member on the other hand. Both gripping sets cooperate so that during the upward swing the first grippers which are to seize the sheet are closed whereas during the downward swing they have either to get open or to change their position with respect to the gripper stop member in order that the collision, for example, with the second gripper set or with the sheet being transferred by said second gripper set, might be avoided.

In order that the above-mentioned relative positions of grippers, fixedly mounted on a pivotable gripper shaft against gripper stop member, might be carried into effect, a cam wheel rotatably and concentrically supported by the swing shaft, has been provided. The cam wheel has been in cooperation with a cam follower keyed to the gripper shaft. Due to the curved periphery of the cam wheel, the cam follower controls the angular positio of the gripper shaft during the swing motion of the gripper set. To control various positions of the swing shaft cam wheel, a second cam is provided on the frame of the printing machine and this second cam controls the first cam by means of a second cam follower rocker in such a manner that the grippers move according to the varying conditions during the swinging cycles.

These known designs have the disadvantage that two cam drives are superimposed for synchronizing the relative motion of the grippers against the gripper stop memher and consequently, a complex and expensive installatlon results. The double cam drive comprises many driving parts, an increased number of successive joints so that the accuracy of the motion transmission is diminished and, on the other hand, the susceptibility to operational troubles is increased. Moreover, the adjustment of both cam drives is time-consuming and complicated. The manufacture of cam curvatures is costly and because of lack of room the cams are difiicult to be installed.

The primary object of this invention is to simplify the structure of the gripper control mechanism so as to reduce the material and installation expenses.

Another object of this invention is to increase the reliability of the sheet gripping operation.

Still another object of this invention is to improve the adjustment of the correct positions of the grippers;

According to the present invention, the aforementioned objects are accomplished in that the axis of the pin joint which connects the coupling rod with the cam follower rocker, is aligned with the axis of the swing shaft when the grippers are in a closed position, and that the adjustment of the gripper system is carried out by means of an ad ustment bolt.

To adjust the cam follower rocker, the adjustment bolt' is simultaneously in a swing shaft bore and in a linking joint bore of the cam follower rocker. To adjust the grippers in the closed position, the adjustment bolt is simultaneously in the swing shaft bore and in the linking joint bore of the coupling rod.

The manner in which the objects of the invention are carried into effect is described below with reference to the attached drawings, wherein:

FIG. 1 is a side view of the sheet gripping system with control mechanism according to this invention, shown in a position with open grippers;

FIG. 2 is a side view according to FIG. 1 showing the grippers in the closed, operating position;

FIG. 3 is a sectional front view, taken in the direction of line A-A of FIG. 2;

FIG. 4 shows schematically the gripper control mechanism in the closed, operating position;

5 is the mechanism of FIG. 4 shown with the open gripping system;

FIG. 6 represents in a side view the adjustment of the cam means;

FIG. 7 is a sectional front view taken along line B-B of FIG. 6;

FIG. 8 shows in a side view the adjustment of the operatmg position of the grippers; and

FIG. 9 is a sectional front view along line C-C of FIG. 8.

The sheet gripper system, as shown in FIGS. 1 to 3, comprises a swing shaft 2 pivotably supported between the side discs of a sheet transfer cylinder 1, a plurality of arms 4 rigidly connected to the shaft 2 and pivotably supporting a gripper shaft 3, a plurality of holders 5 rigidly connected at an angle to the arms 4, a gripper stop rail 6 carried by said holders 5, a plurality of grippers 7 fixed to said gripper shaft 3 so that the gripping fingers impact on said gripper stop rail 6 and seize the sheet in a manner known in itself. This arrangement, as a whole, represents a sheet turning device.

If the swing shaft 2 is turned with respect to the transfer cylinder (by means of a drive means not shown in the drawings), the arms 4 together with gripper shaft 3 and grippers 7, as well as holders 5 with the gripper stop rail 6, are swung toward the center of the transfer cylinder 1 and, consequently, the sheet may be transferred to a second gripping system (not shown).

A swing lever 9 is keyed to the end of the gripper shaft 3. The lever 9 is hinged by means of a pin joint 10 to a coupling rod 11. The coupling rod 11 is hinged at its opposite end to the cam follower rocker 13. The rocker 13 oscillates about the pivot 14 which is fixedly attached to the side disc of the transfer cylinder 1. The end of the rocker 13, which engages with the cam circumference 18, is provided with a roll follower 15. The cam 17 is mounted on the frame 16 of the printing machine in such a manner that the roll follower is coplanar with the cam 17. During rotation of the transfer cylinder 1 the roll follower .15 follows the cam circumference 18 and, as a consequence, the cam follower rocker 13 rocks according to the curved contour of the cam circumference 18. The motion of the rocker 13, controlled in the above described manner, passes over a coupling rod 11 on a swing lever 9 which is keyed to the gripper shaft 3. The grippers 7 which are fixed on the gripper shaft 3 too, move in accordance therewith. In this way there is produced by means of the coupling rod 11 a motional coupling between the swing lever 9 and the cam follower rocker 13. The roll follower 15 is urged against the cam circumference 1 8 by means of a torsion-bar spring .19, which is fixed at one end to the cam follower rocker 13 and at the other end to the clamp socket 20.

Now referring to FIGS. 4 and 5, the operation of the sheet gripper control mechanism is as follows:

If, in the case of closed grippers 7, the center point A of the pin 12 and the center point M of the swing shaft 2 are aligned one to another (FIG. 4), then while the whole sheet turning system is swinging up and down around the swing shaft 2, the gripper fingers 7a are moving in a circular path around the center point M. However, with regard to the gripper stop rail .6, the gripper fingers 7a does not execute any relative motion. Only if the center point A is out of alignment with the center point M, so the grippers 7 get to the open position.

Due to this novel and particular feature of the motional coupling between the rocker 13 as a primary drive and the grippers 7 as a driven part, a control of the swinging grippers 7 can be accomplished in any desired position; the cam 17 has only to be provided with curvatures on its circumference 18, corresponding to the open and closed position of grippers 7.

On the other hand, if the center points A and M should not be in alignment with each other when the grippers 7 are closed, then the gripping fingers 7a would travel on a compound trajectory and would vary continually their relative positions against the gripper stop rail 6 during the swinging motion of the sheet turning system. However, owing to the manufacturing inaccuracy, at best at closed positions of grippers 7 the center points A and M will be aligned. To compensate such small defects and to secure correct seizing of the sheets in all positions of the sheet turning system, the grippers 7 in closed position are pressed by means of springs as known from prior art.

Since the position of the center point A is critical for the closed position of grippers 7, it is necessary during the assembly to check by means of an adjustment bolt 21, whether the center point A and M are aligned.

To check the accuracy of the curved cam circumference 18, the adjustment bolt 21 is first inserted into the joint bore 22 of the cam follower rocker 13 and, at the same time, into the axial bore 23 in the swing shaft 2 (FIGS. 6 and 7). Due to this action, the center points A and M are in alignment one to another, the cam follower rocker 13 is in a fixed position and it is possible to test whether the roll follower 15 follows the cam circumference 18 in due order. To adjust the grippers 7 in the closed position, the adjustment bolt 21 is at the same time inserted into the bore 24 of the coupling rod .11, so that the bore 24 is aligned with the bore 23 of the swing shaft 2.

After the adjustment of grippers 7 and the cam follower rocker 13, the adjustment bolt 21 will be removed and the cam follower rocker 13 is connected to the coupling rod 11 by means of a pin 12, by which action the gripper control mechanism is prepared for the operation.

In the above-described embodiment of this invention, the novel gripping control mechanism is disclosed in conjunction with the sheet gripper system. However, the same mechanism can be also employed for controlling the sheet turning operation in conjunction with the suction system in the printing machine. Moreover, the shown and described embodiment is only to be considered as an example as various variations are conceivable within the scope of this invention.

What is claimed is:

1. A control mechanism for a sheet gripping system having a swing shaft pivotably supported on a transfer cylinder of a printing machine, said swing shaft carrying both a hinged gripper shaft having at least a fixedly mounted gripper, and a fixedly mounted gripper stop rail opposite to said gripper, said control mechanism comprising a cam supported by the frame of said printing machine, a cam follower rocker pivotably supported on said transfer cylinder, a swing lever keyed to said gripper shaft, and a coupling rod pivotably linking said swing lever with said cam follower rocker.

2. The control mechanism according to claim 1 wherein in case of closed grippers the center point of said swing shaft is aligned with the center point of the joint connecting said cam follower rocker with said coupling rod.

3. The control mechanism according to claim 2 Wherein said joint is a pin joint, whereby said swing shaft is provided with a coaxial bore for inserting the adjustment bolt.

4. A method for adjusting the control mechanism of a sheet gripping system mounted on a pivotable swing shaft on a transfer cylinder of a printing machine having pivotable grippers controlled by a cam follower rocker linked to the grippers through a coupling rod and driven by a separate cam, comprising the steps: aligning temporarily the center of the joint between said coupling rod and the cam follower rocker with the axis of said swing shaft; adjusting the angular position of the cam for a closed position of the grippers; adjusting said gripping system into the closed position of the grippers and, at this position, setting the joint between said coupling rod and said grippers.

References Cited UNITED STATES PATENTS 2,865,289 12/1958 Fowlie 10l409 RICHARD E. AEGERTER, Primary Examiner U.S.Cl. X.R. 

